Once a motor neuron has fired, all the muscle fibers in a muscle contract.
A motor neuron and all the muscle cells that it stimulates are referred to as a motor end plate.
Peristalsis is characteristic of smooth muscle.
A contraction in which the muscle does not shorten but its tension increases is called isometric.
During isotonic contraction, the heavier the load, the faster the velocity of contraction.
One of the important functions of skeletal muscle contraction is production of heat.
Although there are no sarcomeres, smooth muscle still possesses thick and thin filaments.
A resting potential is caused by a difference in the concentration of certain ions inside and outside the cell.
The effect of a neurotransmitter on the muscle cell membrane is to modify its ion permeability properties temporarily.
Which muscle cells have the greatest ability to regenerate? A) skeletal B) cardiac C) smooth D) no muscle can regenerate
Most muscles contain ________. A) muscle fibers of the same type B) a mixture of fiber types C) a predominance of slow oxidative fibers D) a predominance of fast oxidative fibers
B) a mixture of fiber types
Which of the following is not a usual result of resistance exercise? A) increase in the efficiency of the respiratory system B) increase in the efficiency of the circulatory system C) increase in the number of muscle cells D) increase in the number of myofibrils within the muscle cells
C) increase in the number of muscle cells
Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period during which the events of excitation-contraction coupling occur. A) contraction B) relaxation C) latent D) refractory
Creatine phosphate functions in the muscle cell by ________. A) forming a temporary chemical compound with myosin B) forming a chemical compound with actin C) inducing a conformational change in the myofilaments D) storing energy that will be transferred to ADP to resynthesize ATP
D) storing energy that will be transferred to ADP to resynthesize ATP
The major function of the sarcoplasmic reticulum in muscle contraction is to ________. A) make and store phosphocreatine B) synthesize actin and myosin myofilaments C) provide a source of myosin for the contraction process D) regulate intracellular calcium concentration
D) regulate intracellular calcium concentration
The striations of a skeletal muscle cell are produced, for the most part, by____ A) a difference in the thickness of the sarcolemma B) the arrangement of myofilaments C) the sarcoplasmic reticulum D) the T tubules
B) the arrangement of myofilaments
Which of the following are composed of myosin? A) thick filaments B) thin filaments C) all myofilaments D) Z discs
A) thick filaments
During muscle contraction, myosin cross bridges attach to which active sites? A) myosin filaments B) actin filaments C) Z discs D) thick filaments
B) actin filaments
Which of the following surrounds the individual muscle cell? A) perimysium B) endomysium C) epimysium D) fascicle
Rigor mortis occurs because ________. A) the cells are dead B) sodium ions leak out of the muscle C) no ATP is available to release attached actin and myosin molecules D) proteins are beginning to break down, thus preventing a flow of calcium ions
C) no ATP is available to release attached actin and myosin molecules
Which of the choices below does not describe how recovery oxygen uptake (oxygen deficit) restores metabolic conditions? A) converts lactic acid back into glycogen stores in the liver B) resynthesizes creatine phosphate and ATP in muscle fibers C) increases the level of lactic acid in the muscle D) replaces the oxygen removed from myoglobin
C) increases the level of lactic acid in the muscle
The oxygen-binding protein found in muscle cells is ________. A) hemoglobin B) ATP C) myoglobin D) immunoglobin
The contractile units of skeletal muscles are ________. A) microtubules B) mitochondria C) T tubules D) myofibrils
one functional unit of a skeletal muscle is_____ A) a sarcomere B) a myofilament C) a myofibril D) the sarcoplasmic reticulum
A) a sarcomere
The the functional role of the T tubules is to____ A) stabilize the G and F actin B) enhance cellular communication during muscle contraction C) hold cross bridges in place in a resting muscle D) synthesize ATP to provide energy for muscle contraction
B) enhance cellular communication during muscle contraction
The role of calcium ions in muscle contraction is to_____ A) form hydroxyapatite crystals B) reestablish glycogen stores C) bind to regulatory sites on troponin to remove contraction inhibition D) increase levels of myoglobin
C) bind to regulatory sites on troponin to remove contraction inhibition
During vigorous exercise, there may be insufficient oxygen available to completely break down pyruvic acid for energy. As a result, the pyruvic acid is converted to ________. A) a strong base B) stearic acid C) hydrochloric acid D) lactic acid
D) lactic acid
When a muscle is unable to respond to stimuli temporarily, it is in which of the following periods? A) relaxation period B) refractory period C) latent period D) fatigue period
B) refractory period
In an isotonic contraction, the muscle ________. A) changes in length and moves the "load" B) does not change in length but increases tension C) never converts pyruvate to lactate D) rapidly resynthesizes creatine phosphate and ATP
A) changes in length and moves the "load"
The muscle cell membrane is called the ________. A) endomysium B) sarcolemma C) perimysium D) epimysium
Smooth muscle is characterized by all of the following except ________. A) it appears to lack troponin B) there are more thick filaments than thin filaments C) there are no sarcomeres D) there are noncontractile intermediate filaments that attach to dense bodies within the cell
B) there are more thick filaments than thin filaments
Muscle tissue has all of the following properties except ________. A) secretion B) contractility C) extensibility D) excitability
Which of the following statements is true? A) Cardiac muscle cells have many nuclei. B) Smooth muscle cells have T tubules. C) Striated muscle cells are long and cylindrical with many nuclei. D) Cardiac muscle cells are found in the heart and large blood vessels.
C) Striated muscle cells are long and cylindrical with many nuclei.
An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is ________. A) the citric acid cycle B) glycolysis C) hydrolysis D) the electron transport chain
The sliding filament model of contraction involves ________. A) actin and myosin sliding past each other and partially overlapping B) the shortening of thick filaments so that thin filaments slide past C) actin and myosin shortening but not sliding past each other D) the Z discs sliding over the myofilaments
A) actin and myosin sliding past each other and partially overlapping
After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction? A) calcium ions returning to the terminal cisternae B) the tropomyosin blocking the myosin once full contraction is achieved C) acetylcholinesterase destroying the ACh D) the action potential stops going down the overloaded T tubules